Surgical cables positioned around bones and the like may be held in desired position by crimps, which are crushed into engagement to retain the cable at a desired position. See Kilpela et al. U.S. Pat. No. 5,415,658, and Songer et al. U.S. Pat. Nos. 4,966,600 and 5,116,340, by way of example.
Current designs of cable and crimp systems, particularly for surgical use, have significant drawbacks.
As a first drawback, there is the possibility in most cable and crimp systems for slippage of the cable in the crimp to take place. This of course can be extremely unfortunate, particularly in the orthopedic field where a crimped cable loop or winding may have been implanted in the patient to support a broken bone. With any crimp slippage, the winding or loop of cable loosens and the tension drops significantly, which can result in major pain for the patient and a bad medical outcome.
As a second drawback, many prior art crimps cannot be easily locked into a cable loop or winding at a desired tension, and then retained precisely at that tension when the crimping pliers are removed. Typically, there is an inevitable drop in the tension as the pliers are removed. Thus, a surgeon typically has to "over shoot" the desired tension, guessing how much of that tension will be lost after the crimping has been completed and the pliers removed. This brings in the significant possibility for tensioning errors. A tension which is too low or a tension which is too high on orthopedic cables can give a bad medical result.
By this invention, a new crimp is provided in which a crimp exhibits better cable retention at lower crimping pressures (as exerted by the crimping pliers), other things being equal. Additionally, the crimping system of this invention, in a preferred form, can provide a more accurate tension to the cable so that there is little or no need to "overshoot" the tensioning of the cable, with the expectation that some of the tension will be lost after the crimp has been applied by the crimping pliers to a cable loop or winding.